mirror_zfs/modules/spl/spl-rwlock.c
behlendo 79f92663e3 Fix race in rwlock implementation which can occur when
your task is rescheduled to a different cpu after you've
taken the lock but before calling RW_LOCK_HELD is called.
We need the spinlock to ensure there is a wmb() there.


git-svn-id: https://outreach.scidac.gov/svn/spl/trunk@68 7e1ea52c-4ff2-0310-8f11-9dd32ca42a1c
2008-04-07 23:54:34 +00:00

50 lines
745 B
C

#include <sys/rwlock.h>
int
__rw_read_held(krwlock_t *rwlp)
{
BUG_ON(rwlp->rw_magic != RW_MAGIC);
if (__rw_lock_held(rwlp) && rwlp->rw_owner == NULL) {
return 1;
}
return 0;
}
EXPORT_SYMBOL(__rw_read_held);
int
__rw_write_held(krwlock_t *rwlp)
{
BUG_ON(rwlp->rw_magic != RW_MAGIC);
if (rwlp->rw_owner == current) {
return 1;
}
return 0;
}
EXPORT_SYMBOL(__rw_write_held);
int
__rw_lock_held(krwlock_t *rwlp)
{
int rc = 0;
BUG_ON(rwlp->rw_magic != RW_MAGIC);
spin_lock_irq(&(rwlp->rw_sem.wait_lock));
#ifdef CONFIG_RWSEM_GENERIC_SPINLOCK
if (rwlp->rw_sem.activity != 0) {
#else
if (rwlp->rw_sem.count != 0) {
#endif
rc = 1;
}
spin_unlock_irq(&(rwlp->rw_sem.wait_lock));
return rc;
}
EXPORT_SYMBOL(__rw_lock_held);